As a result of compression of the combustion air in a turbocharger of a motor vehicle, the air is heated. Hot air requires a larger volume within a container relative to cold air and in order to provide the greatest possible air mass for combustion in an internal combustion engine, an thus to increase the power and efficiency of said internal combustion engine, the temperature of the supplied air may be reduced further by way of charge-air coolers. Charge-air coolers may typically be arranged within an intake tract of an engine between a turbocharger and an inlet valve. In a case where water-cooled charge-air coolers (WCAC), are used, the heat may be released into a dedicated water-cooling circuit. In this case, a cooling circuit comprises not only the WCAC, but also a cooling radiator 2 and a pump 3 for the cooling fluid, water.
The charge air may then be mixed with the exhaust gas of an internal combustion engine by way of an exhaust gas recirculation (EGR) arrangement. This may serve primarily for reducing the emissions of nitrogen Oxides (NOx). Furthermore, in a case of Otto-cycle engines, exhaust-gas recirculation may be conductive to reducing charge-exchange losses, and thereby may also reduce fuel consumption. In a case of low-pressure EGR, an exhaust gas may be discharged downstream of an exhaust-gas after-treatment arrangement, and may be introduced upstream of a turbo compressor. Some of the exhaust gas may then flow from a turbo compressor into the internal combustion engine through a charge-air cooler.
However, the inventors herein have recognized potential issues with such systems. As one example, one potential drawback presented by charge-air coolers is that condensation water may form within the coolers. A feature of the present disclosure provides that water which may be contained in gaseous and droplet liquid form within inducted combustion air and/or within recirculated exhaust gas may be condensed.
The exhaust gas in particular, may also comprise other substances that may react with the condensation water in a way that produces acid products. In instances such as this, it may for example, be possible for sulfur compounds within an exhaust gas to react in a way that produces sulfuric acid, wherein the pH value may be between 1.5 and 2. This may lead to corrosion of the metal constituents of the charge-air cooler (cooling ribs, cooling hoses, and other parts comprising aluminum or steel), whereby the durability thereof may be jeopardized. It may also be possible, for example, for constituent parts comprised of brazing materials used during the production of the charge-air cooler to become detached and to cause punctiform corrosion. It is thus important for condensation water to be substantially removed from the charge-air cooler in order to limit the risk of corrosion damage. Furthermore, in a rest state of an engine, condensation water may pass from the charge-air cooler to a point upstream of the swept volume of the internal combustion engine, and here, may result in starting problems and serious potential engine damage.
In one example, the issues described above may be addressed by a method for an internal combustion engine with an exhaust-gas recirculation arrangement, wherein a cooler device which may be connected via a coolant circuit to a charge-air cooler imparts a cooling effect through maximum cooling of a charge-air cooler. In this way, the water that may be present in a gaseous state or in droplet liquid form within a charge-air cooler may be condensed and furthermore, with the condensate that may be present, as it runs off under the action of the force of gravity into a lower region of a charge-air cooler, condensation water may be purged from a charge-air cooler, and in the process, substances with a potentially corrosive action may be washed out.
It will be appreciated that in the present disclosure, the term “condensate” may be used synonymously with condensed water and the terms may be used interchangeably.
As one example, the method described herein, may be further desirable in part because the removal of condensate in the shut-down state of a motor vehicle, may provide that no condensation water may pass from a charge-air cooler to provided inlet valves and may not result in drawbacks such as difficulty starting the engine and/or engine damage.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.